Computer virtualization is a technique that involves encapsulating a physical computing machine platform into a virtual machine that is executed under the control of virtualization software on a hardware computing platform. Virtualization software enables multiple virtual machines to be run on a single hardware computing platform, and can manage the allocation of computing resources to each virtual machine in accordance with constraints and objectives.
A set of hardware computing platforms can be organized as a server cluster to provide computing resources for example, for a data center. In addition, supporting technology can move running virtual machines between servers in the cluster; an example of this supporting technology is sold as VMware VMotion™ by VMware, Inc. of Palo Alto, Calif. In addition, server cluster virtualization management software that incorporates cluster resource management technology can determine initial and ongoing locations of virtual machines on hardware computing platforms in the server cluster, and can manage the allocation of cluster computing resources in accordance with constraints and objectives. An example of this server cluster virtualization management software is sold as VMware Distributed Resource Scheduler™ by VMware, Inc. of Palo Alto, Calif. In addition, the server cluster virtualization management software can request that a server in the cluster power itself down, and can use mechanisms available in the marketplace to remotely power-on a server that is powered down. An example of this power management software is sold as the VMware Distributed Power Management feature within the VMware Distributed Resource Scheduler by VMware, Inc. of Palo Alto, Calif.
Server clusters consume significant power. The cost of that power is a major expense in operating a server cluster, and generating that power can have an environmental impact.